Are you comfortable? Maybe you are standing or lying down. Wherever you are, just tap your right foot for a moment. Thought, done. How did you do that? You read the text and thought about tapping your right foot. Your brain then sent a signal down the nerve cords of the spinal cord to your lower leg and foot. There, exactly those muscles that are needed for the movement were tensed. "Nothing special," you might say. I think: a remarkable achievement.
In paraplegics and tetraplegics, the spinal cord is severely damaged, so that the signal from the brain no longer reaches the muscles below. As a result, they can no longer walk – except for a few who have learned to walk again thanks to modern medicine and technology. Grégoire Courtine, Jocelyne Bloch and their team from EPFL, the University of Lausanne and the University Hospital of Lausanne were able to help some of them.
The scientists' principle sounds quite simple: Courtine and Bloch implanted electronic sensors in the paralysed person's upper spinal cord. These sensors sense when an impulse comes from the brain and direct it past the damaged area to the lower part of the spinal cord. There, the nerves transmit the impulse to the muscles in the legs, and they then begin to move. So, in principle, the damaged area is simply bridged.
It is of course more complicated in detail. For us to be able to walk, dozens of muscles in our legs, feet and joints must work together like a clockwork. It took us all dozens of months to learn it! Even the paralysed patients in French-speaking Switzerland had to practice hard until it worked. Their leg muscles had regressed over the years in the wheelchair. In addition, the sensors first had to learn when which nerve fibres were active.
It gets even more exciting: Gradually, the electronic support could be switched off. In the spinal cord there are many intact nerve fibres left, and they are beginning to take over the tasks of the electronics! That's why paralysed people today can walk a few steps without support. The electronics helped the nervous system to reorganize itself. Nerve fibres have even grown back. There are videos of David Mzee on the Internet: He walks a little clumsily, but it is a phenomenal success that he can walk again at all.
For Courtine and Bloch, such successes are an incentive to continue research. They are currently working on further improving their system. And they have expanded their field of research. Now they also want to help people had a stroke or suffer from Parkinson's disease. In Parkinson's disease or a stroke, basically the same thing happens as in paralysis: nerve conduits are destroyed. And theoretically, it should be possible to bridge these defective areas.
Of course, it will be years before the research duo from Western Switzerland are ready to deliver their first results. It would be great if it worked!
The article originally appeared in SonntagsBlick.